Process of producing a metal-dust mixture



Oct. 9, 1928. 1,687,034

MT'H. NEWELL PROCESS OF PRODUCING A METAL DUST MIXTURE Filed April 11. 1927 ATTORNEY Patented Oct. 9, 1928.

MINTON H. NEWELL, OF SA N'FBANCISCO, CALIFORNIA, ASSIQNOB TO THE ALLOYS' COMPANY, OF SAN FRANCISCO, CALIFORNIA, A CORPORATION OF CALIFORNIA.

UNITED STAT S "a lication filed April 11,

The invention relates to an improvement in processes of producing a metal dust mix- .ture, and more articularly to an improved process of pro ucing a zincdead dust.

Metal dust has found wide application in the arts. Usually the dust is composed of the single .metal. 'A demand has grown up, however, for a compound. metal dust,

\ that is, a dust composedof two or more metals. For example, a dust composed'of zinc with a certain proportion of lead has the proper quantity of lead in a soluble f form, such as acetate, and then add the zinc dust to the solution. It has been found difiicult to regulate properly the amount of lead added to the solutionin this man? her to effect the desired reaction with the zinc, hence thereis a deman'd in the cyanide process industry for azinc dust containing the proper proportion of lead. Up to the present time, however, no satisfactory process has been devised for producing a zinclead mixture of proper roportions, and of the requisite degree of fineness.

One object oi the present invention is to provide a process of producin 'a-metal dust mixture in which the ingredients will be properly pro ortioned and of the requisite fineness of Sn division. A more specific object of the'invention is to produce a zinc-' leaddust mixture in which the amount of metallic lead will be properly proportioned to the zinc. To'these ends, the invention, in one aspect, consists in producing a metal vapor by heating a metal in a retort tothe point of vaporization, and introducing into the hot metal vapor a metalliferous oxide of which the metallic elementdifiers from the metal of the vapor and is capable of releasing oxygen by action of thecho t vapor.

I prefer to use a metalliferous oxide because Ihave foundby previous experiments (see my U. S. Patent 1,456,035, dated May 22, 1923) that the introduction of oxygen in controlled amounts 1: e metal vapor ac-- 'celerates the condensation of the vapor and remotes the condensin of; the vapor. in

l 1 p rt s than can" s cured without "bines with -a portion of t condensing chamber from rnocnss on rnonucme A METAL-DUST JuIx'rUnE.

1927. Serial No. 182,972.

introducing oxygen into the vapor. I have now discovered ,that'by introducing into the metal vapor a finely divided metalliferous oxide containing the metal I desire to mix with the metal to be-condensed from the vapor, I can secure substantially 'the required amount of oxygen to cause the vapor to condense in the requisite degree of fineness, and at the same time obtain a finely divided metallic dust from the decomposed oxide. If the oxidedoes not contain the proper amount of oxygen to cause the vapor to condense in the requisite degree of fineness, I introduce into the mixture a sufiicient additional amount of oxygen from external sources, as from asupply of oxygen maim tained for .this purpose or from the at mosphere. because they can be on decomposition yiel dustthan can be obtained by grinding the metal itself. f a

Metal oxides are also desirable dground very fine and amuch finer metallic I To 'roduce a zinc-lead mixture, the im prove process consists in vaporlzing the- .zinc and introducing into the zinc vapor the proper amount of'finely'divided leadoxide to give the re uired amount of metallic lead in the zincead dust .mixture. The zinc vapor acts on the lead oxide and-.de-

composes it, forming finely divided metallic lead and liberating oxygen which com-' e zinc vapor to form zinc oxide. The mixture of zinc vapor, metal lead and zinc oxide .is then cooled sufiiciently rapidly to cause the zinc vapor to condense in fine particles in intimate contact with the finely divided metallic lead. In practicing the process to roduce the lead-zinc dust mixture, I heat t e zinc in a retort, the mouth of which discharges into a condensin chamber,'the walls of which are preferabdy composedof some substance which rapidly radiates heat, such as iron or steeL- The retort is preferablyinclined at an angle upwardly so that it will discharge the stream of zinc vapor or fumes upwardly into the condensing chamber. As the stream of 'zinc vapor enters the condensing chamber, it becomes cooler and a portion of it/ condenses out into articles of metallic zinc. Into this streamo zinc va er'enterin the the mouth 0 the retort I mt'roducea continuous sup 1y of finely div ded lead 03 601711 11 8 111 posed by the vapor. The mixture of vapor,

metallic zinc, metallic lead and zinc oxide' is preferably circulated within the condensing chamber to accelerate the condensation. This circulating mixture will in practice receive and carry with it some ofethe finely divided lead oxide which will thereby be acted upon by the hot zinc vapor and lead dust mixture, may be practiced in the U decomposed into the metallic lead and oxygen If the oxygen introduced into the mixture of vapor and metallic oxide particles in this manner is not sufficient to promote the proper degree of fineness of condensation of the z1nc vapor, I then add the required amount of Oxygen trom an external source.

The improved process in its more specific and preferred form for producing a zinc apparatus shown in the taccompanying' drawingsof which Fig. 1 is a side elevation of the condensing chamber with its accessory apparatus and showing in section the fur nace for heatin the zinc and the means for feeding the lea oxide, and Fig.2 is a top plan of the parts shown 'in Fig. 1.

The apparatus comprises a retort 1 of usual form located within a furnace 2. The retort 1 is inclined at an angle so that its mouth 3 projects through the wall 4 of the furnace 2 and enters the hood 5 which serves as a connection between the furnace 2 and the condensing chamber or condenser 6. j A tight joint 7 is established/between the hood 5 and the wall 4 of the furnace 2 by luting the joint. As the vapors from the retort l enter the condenser 6 they begin to condense the condenser.

retort.

and the mixture ofi vapor and particlesof metal zinc are circulated within the condenser by means of the fan 8 located on top ofx The intake 10 of the fan opens into the condenser, and a discharge pipe 9 is directed downwardly within the condenser, terminating above the mouth 3 of the retort 1, so as to direct the mixture of vapors and metal particles into the hot zone of zinc vapor ,above the mouth of the The fan 8 is driven by the motor 11. The finely divided lead oxide is introduced into the upper part of the hood 5 through the discharge opening 12 of a hopper 13 pro- .vided with the feed mechanism 14' which may be driven from any convenient'source. It is preferred to locate the lead oxideieeding devicesin the top 'ofthe hood 5 so that l as the powdered lead oxide falls down into a the hood 5 it may disseminate in the mix- A retort 1. Thus there is aconstantjstream of j ture of zinc vapor and metallic zinc particles and be drawn by the steam issuing from the mouth of the discharge pipe 9 into thehot zone of zinc vapor near the mouth 3 of zinc vapor, particles-of metallic zinc and particles of lead oxide entering the hotizinc vapor near the mouth of the retort 1, in which zone thefllcdd oxide is. decomposed forming metallic lead and liberating oxygen which combines with a portion of-the zinc vapor to form zinc oxide. As a result of these reacti0ns,'after the apparatus has been put into full operation,-there is maintained within the condenser 6a circulation of zinc metallic lead and particles of zinc oxide, it

j being understood that the lead oxide will be decomposed when it is brought within the hot zone near the mouth 3 of the retort '1.

To prevent ingress of oxygen into the condenser 6 through the hopper 13, a sufficient amount of lead oxide is maintained within the hopper.

If the oxygen liberated from the lead oxide is not sufficientin, quantity to gilect r-Q I vapor, particles of metallic zinc, particles of the requisite-degree of oxidation of the zinc,

additional oxygen may 0e: drawn into the mixture within the condenser 6 'by means of the breather 15 connected with the condenser by the pipe-fitting 16. An additional means of introducing "oxygen from the air is provided by the valve controlled pipe 17. A0- cess to the interior of the condenser 6 may be had through theplugged opening18. As zinc condenses in conjunction with the metallic lead and zinc oxide it falls'out of the circulating mixture and accumulates in-the.

cone shaped bottom -19 of the condenser,

froin which it is withdrawn through the dis charge door 20. I a

It will be understood that by regulating the quantity of finely diyided lead oxide rel atively to the amount of zinc the resultant dust will contain the desired relative quantities of zinc and lead.

.Having thus described the invention, what I claim as new is 1. The process of producing a zinc-lead dust which consists in vaporizing zinc, de- VcompoSing lead oxide in the zinc vapor and then cooling the mixture su-fliciently rapidly metallic lead and oxygen in the zinc vapor,

and then' cooling the mixture sufliciently rapidly to condense the zinc in a fi nely divided condition. k

4. The process of manufacturing zinc-lead dustwhich consists in vaporizing zinc, conducting the zinc vipor into a condenser, v

maintaining a circ lationwithin the con- .denser, an introducing finely divided lead 5. In the pmoess of manufacturing zinclead dust including producingv zinc vapor 5 containing particles of metallic zinc in suspension, the steps of introducing finely divided lead oxide into the'mixture of vapor 1* nd tallic zincand then introducing the mixture formed into a relatively hot, pui'e .10

zinc va 1'. 1 I

6 e process of producing zinc-leadust which consists in mixing finely divided f zinc'and finel' .divided lead oxide ata temperature suflizient to decompose the lead oxideand then cooling the mixture.

a. s MIN TON H. NEWELL. 

